Global warming with its increase in CO2 levels has become a social issue. Thus, it is necessary to reduce CO2 emissions and reduce excessive emitted CO2 through green campaigns, for example, planting plants. For this reason, objectives have been established to accurately understand the latest distribution of CO2, plants that absorb CO2 by photosynthesis, and the distribution of chlorophyll.
Conventionally, the amount of CO2 is directly observed by instruments with which, for example, aircraft are equipped. However, because the observed values obtained by the instruments through their measurements is information limited to a specific point, the spatial actual amount and the distribution of chlorophyll cannot be uniformly understood. Thus, the amount of CO2 on the earth cannot be accurately known. Therefore, a definite policy of green schemes cannot be established and only limited measurements have been taken for in regions where tree-planting can be carried out.
However, the Greenhouse Gases Observing Satellite (GOSAT) and the US Orbiting Carbon Observatory (OCO), which can observe the CO2 concentration on the earth, have been developed in recent years. Observations by the GOSAT and OCO allow us to know the distribution of CO2. Accordingly, global distribution data on the CO2 concentrations can be obtained.
For example, Patent Document 1 discloses, as conventional technologies related to the concentration distribution of CO2, a planting support system that can carry out appropriate planting schemes in consideration of the chronological changes of plants by calculating the amount of CO2 in the atmosphere in accordance with planting with regard to each type of plant.    Patent Document 1: Japanese Laid-open Patent Publication No. 2000-12345